Popular for historic and vintage transmissions, like Mid-1930s to early-1950s synchro-equipped gearboxes in cars and trucks, 75W140 NS is known to help with noisy or rough shifting in troubled A-833 Dodge/Plymouth 4-speed transmissions from 1964 to 1969. It is also used as an option for noisy transmissions when mixed with 75W90NS or MT-90 (to bring viscosity level up) and can also used in clutch-type limited slip differentials in racing for maximum lock up (some users add Limited Slip Friction Modifier in small doses to customize slippage).